RU2033840C1 - Device for liquid degasification - Google Patents

Abstract

FIELD: mechanical engineering. SUBSTANCE: device has impeller pump. A worn is mounted in the inlet branch pipe of the pump. The device is equipped with conic gas intakes uniformly set along the circumference of the inlet branch pipe in front of the worn and disposed in the plane perpendicular to the pump axis of rotation. The intakes have axles parallel to the tangents to the branch pipe circumference in the place of the intake mount. The greatest diameter of the intake makes up 0.084-0.09 of the worn diameter. The distance from the edge of the greatest diameter of the intake to the worn and to the branch pipe walls makes up 0.02-0.025 of the worn diameter. The device has an assembled collector, exhaust pipes connecting the intakes and the assembled collector and a partition in the shape of a frustum. The partition is mounted in the branch pipe in front of the intakes. The smaller foundation of the partition is directed towards the intakes. The axis of symmetry of the partition coincides with the branch pipe axle. The greater diameter of the partition is equal to the inner diameter of the branch pipe. The plane of the smaller diameter of the partition is disposed at a distance of 0.1-0.115 of the worm diameter from the branch pipe wall. The distance from the plane of the smaller diameter of the partition to the plane of the intake axles is equal to 0.072-0.100 of the worm diameter. EFFECT: facilitated manufacture. 2 dwg, 2 tbl

Description

 The invention relates to pump construction, can be used for any vane pumps that pump aerated liquids.

 Vane pumps operate reliably on clean liquid or slightly slightly aerated liquid, where the gas volume at the pump inlet at a speed of less than 820-1030 1 / s is 5-10% of the volume of the pumped liquid. Increasing the degree of aeration to a value that exceeds the permissible value leads to a breakdown in the pump. To ensure its operability, it is necessary to reduce the degree of flow aeration in front of the pump.

 To deaerate the fluid, special gas-venting devices are installed at the pump inlet. The closest in technical essence and the achieved result is a device for degassing liquids, including a vane pump, a screw is installed in the inlet pipe [1] This device eliminates additional energy costs for swirling the flow in the modes with developed reverse currents, and gas is removed from the flow to axial wheel. However, the efficiency of the device is small, since its testing showed that a gas-liquid mixture with a very large (up to 25%) amount of working fluid is removed through a hollow intake installed in the center of the gas-liquid flow, and these losses increase significantly with a decrease in the intensity of reverse currents.

 The aim of the invention is to increase the efficiency of deaeration of the fluid flow in all modes of operation of the pump with reverse currents at its inlet.

 The goal is achieved by the fact that stagnant zones are created at the inlet pipe of the vane pump operating in reverse current modes in the accumulation zone of gas inclusions in the peripheral part of the flow, from which gas is sucked out. To do this, in a stagnant zone in a plane perpendicular to the axis of rotation of the pump, conical gas intakes are installed with axes of symmetry parallel to the tangent to the circumference of the pipe at the installation site of the intakes, the largest diameter of the intake is equal to 0.084-0.09 of the screw diameter and decreases in the direction against rotation of the rotor, the distance from the edge of the largest diameter of the intake to the screw and to the walls of the nozzle is 0.02-0.025 of the diameter of the screw, while the device is equipped with a prefabricated collector and outlet pipes connecting the intakes and the prefabricated the collector, and a partition in the form of a truncated cone installed in the pipe in front of the intakes, the smaller base of the partition is closer to the intakes, the axis of symmetry of the partition coincides with the axis of the pipe, the larger diameter of the partition is equal to the inner diameter of the pipe, the plane of the smaller diameter of the partition is 0.1- 0.115 screw diameters from the degree of the nozzle, and the distance from the plane of the smaller diameter of the partition to the plane of the axes of the intakes is 0.072-0.1 screw diameters.

 Figure 1 presents the proposed device; figure 2, view A in figure 1.

In figure 1, 2 are indicated: 1 conical intakes located in a plane perpendicular to the axis of rotation of the pump; 2 screw wheel of a screw centrifugal pump; 3 outlet pipes; 4 prefabricated collector; 5 partition in the form of a truncated cone
The proposed device operates as follows.

,
где tg β_п тангенс угла входа потока на лопатки на данном режиме;
tg β_л тангенс угла установки лопатки.When the screw centrifugal pump operates at different flow rates, there are those in which some of the liquid at the periphery of the screw is ejected towards the main flow Q _n at a distance l _o . Then this part of the liquid, called the reverse current, rotates 180 ^° and again goes to the pump inlet in the direction of the main flow. The presence and intensity of reverse currents are characterized by the value of the discharge parameter
q

,
where tg β _{p the} tangent of the angle of entry of the flow on the blades in this mode;
tg β _l tangent of blade angle.

 At q close to zero, the intensity of reverse currents is maximum, with increasing q it decreases and at q ≈ 0.5, the reverse currents practically disappear.

 The operation of a screw centrifugal pump in reverse current modes is widespread, since it leads to an improvement in the cavitation qualities of the pump.

As visual observations have shown, the reverse current zone has a vortex structure, forming a single whole with the vortex flow systems at the inlet to the auger. The gas in the gas-liquid flow, when entering the auger wheel, is actively concentrated in the vortex systems and is discharged into the reverse current zone, where the gas concentration is several times higher than in the pump inlet flow Q _n . The main flow Q _n , which occupies the entire cross-section in front of the pump, is forced to flow around the formed reverse currents before entering the screw; the flow cross-section is narrowed. In addition to the axial velocity, the fluid particles in the reverse current zone also have a large peripheral velocity, i.e. the entire reverse current zone rotates in the direction of rotation of the wheel. Moreover, if the axial speed is 1-1.5 m / s, then at a pump speed of n = 4000 rpm and a screw diameter D _w = 100 mm, the peripheral speed in the reverse current zone is U ≈18 m / s.

 Thus, at the periphery of the screw there is a highly aerated fluid flow, rotating at a considerable speed in almost the circumferential direction.

 Studies have shown that if you create stagnant zones in a rotating layer of reverse currents in which local rarefaction regions arise, then free gas inclusions from a moving gas-saturated vortex layer are concentrated in stagnant zones, from which it is possible to extract them. In order to create such stagnant zones in a gas-saturated flow at the periphery of the screw, conical intakes 1 are installed, which flow around from a smaller diameter to a larger one, and the axis of the intake is parallel to the tangent to the circumference of the pipeline at the installation site of the intake. When the flow around the intake 1 by the stream behind its large diameter, a cavity K is formed, filled with gas from the stream. Gas passes through the pipes 3 connecting the intakes to the collector 4 into this collector, and from there into the collection tank, where a lower pressure is created than in the stream.

 The removal of gas from the cavity is immediately compensated by the arrival of new portions from the stream in its place, the process becomes continuous, which ensures a decrease in gas saturation of the liquid.

The gas inclusions present in the flow Q _n entering the auger wheel 2 are captured by the vortex systems present in the auger wheel and return flows from the auger to the periphery of the pipeline into an annular rotating zone in which the gas content substantially exceeds the gas content of the main flow Q _n .

 When circulating inlets 1 by reverse currents around the large diameter of the conical intake, a stagnant zone of cavity K. is formed. Gas flows from the zone of reverse currents into this cavity and is evacuated through pipe 3 to collector 4 through pipe 3, from where it is removed.

 The proposed device is designed for one of the developed fuel supply systems. Geometric ratios were obtained experimentally by optimizing its characteristics under conditions of operation in a wide range of the flow rate parameter q and a high level of gas saturation of the component.

 The gas-saturated liquid layer is located on the periphery of the inlet pipe. It is in this zone that hollow intakes serving for gas extraction are arranged uniformly around the circumference, oriented in the flow in such a way that rarefaction regions form behind them. The experiments showed that at the same flow rate and degree of aeration, the maximum amount of gas can be concentrated in stagnant zones and with a smaller amount of liquid taken from the stream with increasing diameter of the intake with a more uniform flow around the intake from all sides. The intake, mounted close to the wall of the inlet pipe, where it is difficult to flow around the upper part of the intake, removes 20-25% less gas than the intake, somewhat remote from the wall. Removing the intake from the screw also reduces the amount of suction gas.

0,077

равным 11,5 см³/с. Вблизи стенки удаляется существенно меньше газа, чем в глубине обратных токов. Непосредственно у стенки

0,6 и лишь при

= 0,02-0,025 составляет 0,8-0,85 от максимального. Можно определить также толщину зоны, где желательно располагать заборники. Приняв, что отбираемый расход не должен быть менее 0,8-0,85 от максимального, получают толщину оптимальной зоны

=

0,11-(0,02-0,025) 0,085-0,09 нижняя граница которой с учетом расстояния от стенки составляет (0,02-0,025)+(0,085-0,09)=0,1-0,115.To determine the optimal diameter of the intake and its distance from the pipeline wall, experiments were carried out with a single intake made of a thin-walled tube with a diameter of 2 mm (wall thickness 0.1 mm), which could move along the radius of the pipeline. At each position of the intake, the amount of gas and liquid removed through it was measured, while the pump worked in the following mode:
n = 4000 rpm; P _in = 1.6 kg / cm ² ; q = 0.328; δ _in = 9%
When deepening the intake by 12 mm (no further deepening was carried out due to the danger of touching with a rotating screw), the maximum amount of gas removed was at l ₂ = 7.7 mm

0,077

equal to 11.5 cm ³ / s. Significantly less gas is removed near the wall than in the depth of reverse currents. Directly at the wall

0.6 and only with

= 0.02-0.025 is 0.8-0.85 of the maximum. You can also determine the thickness of the zone where it is desirable to place the intakes. Assuming that the selected flow rate should not be less than 0.8-0.85 of the maximum, get the thickness of the optimal zone

=

0.11- (0.02-0.025) 0.085-0.09 whose lower boundary, taking into account the distance from the wall, is (0.02-0.025) + (0.085-0.09) = 0.1-0.115.

0,02. Очевидно, что это в обоих случаях связано с ухудшением обтекания заборника у стенки.At the same pump operating mode, similar experiments were carried out to deepen a conical intake with a diameter of 8.5 mm. As for a two-millimeter intake in the immediate vicinity of the wall, the amount of gas removed is significantly less than the maximum and equal to 0.85 _{Q gmax} also at

0.02. Obviously, in both cases this is due to the deterioration of the flow around the intake at the wall.

и выбрано равным 0,02-0,025.Based on the described experiments, the distance

and selected equal to 0.02-0.025.

равным 117 см³/с.The maximum amount of gas removed by the intake D = 8.5 mm was at

equal to 117 cm ³ / s.

количество удаляемого газа уменьшается.With further increase

the amount of gas removed is reduced.

 Comparison of test results with intakes D = 2 and 8.5 mm allows you to determine the optimal diameter of the intake.

= 0,085-0,09. Очевидно, что диаметр заборника должен быть равен толщине этого слоя, т.е.

=0,085-0,09. Такой выбор диаметра заборника подтверждается и экспериментами с заборником D=8,5 мм. При максимальном количестве отобранного газа

= 0,03= 0,03 нижний край заборника находится от стенки на расстоянии

+

= 0,03 + 0,085 0,115
Дальнейшее увеличение

ведет к снижению Q_г. Нижняя граница оптимальной зоны примерно на 20% шире толщины расчетной зоны обратных токов, т.е. оптимальная толщина зоны обратных токов захватывает частично участок с противоположным направлением осевых скоростей, где, как показали визуальные наблюдения, сконцентрировано много газа. Дальнейшее заглубление заборника приводит к проникновению в активный поток, где количество газа существенно меньше. Потому выбрана относительная величина диаметра заборника

= 0,085-0,09
Для определения оптимального расстояния

проводили эксперименты с заборником D=8,5 мм, отодвигая его от шнека изменением толщины прокладки S₁. Первоначально заборник установили на расстоянии

, аналогично

, исходя из необходимости хорошего обтекания заборника и исключения касания его о шнек. Испытания проводили при q=0,328 и q=0,43. При удалении от шнека количество отбираемого газа убывает, причем тем быстрее, чем меньше интенсивность обратных токов (т. е. чем больше q). Поэтому в заявке величина расстояния

выбрана равной

=

= 0,02-0,025
Размеры заборников, выбранные указанным способом для средней величины q= 0,3, обеспечивают улучшение газоотделения и при q<0,3, так как уменьшение q увеличивает интенсивность обратных токов, расширяет толщину слоя обратных токов и количество накопленного в нем газа. При q>0,3 и толщина слоя, и количество газа постепенно уменьшаются, заборник может частично выйти из зоны обратных токов, газоотделение уменьшается. Для интенсификации обратных токов, а следовательно, и улучшения газоотделения на режимах q>0,3, вводится коническая перегородка. Кроме улучшения газоотделения коническая перегородка устраняет полностью возможные кавитационные колебания в насосе и в зависимости от диаметра конуса, т.е. от размера

, можно улучшить или ухудшить энергетические характеристики насоса. Чтобы избежать возможного ухудшения характеристик, размер

выбран таким образом, чтобы конус не был заглублен в поток больше, чем заборники, т.е.Table 1 presents the results of such a comparison. It can be seen that with an increase in the diameter of the intake by 4.25 times, the amount of liquid removed increased approximately in the same ratio (5.35), and the amount of gas removed increased by 15.4 times, i.e. in proportion to the square of the ratio of diameters, and the ratio of selected components increased by almost 3 times. Thus, the installation of large-diameter intakes is more favorable for deaeration of the flow. The optimal layer thickness for the location of the intakes

= 0.085-0.09. Obviously, the diameter of the intake must be equal to the thickness of this layer, i.e.

= 0.085-0.09. This choice of the diameter of the intake is also confirmed by experiments with the intake D = 8.5 mm. With the maximum amount of gas taken

= 0.03 = 0.03 the lower edge of the intake is at a distance from the wall

+

= 0.03 + 0.085 0.115
Further increase

leads to a decrease in Q _g . The lower boundary of the optimal zone is approximately 20% wider than the thickness of the calculated zone of reverse currents, i.e. the optimal thickness of the reverse current zone partially captures the plot with the opposite direction of the axial speeds, where, as shown by visual observations, a lot of gas is concentrated. Further deepening of the intake leads to penetration into the active stream, where the amount of gas is much less. Therefore, the relative value of the diameter of the intake

= 0.085-0.09
To determine the optimal distance

experiments were carried out with a fence D = 8.5 mm, moving it away from the screw by changing the thickness of the gasket S ₁ . Initially, a fence was installed at a distance

similarly

, based on the need for a good flow around the intake and the exclusion of touching it on the auger. The tests were carried out at q = 0.328 and q = 0.43. When moving away from the auger, the amount of gas taken off decreases, and the faster, the lower the intensity of the reverse currents (i.e., the greater q). Therefore, in the application, the distance

selected equal

=

= 0.02-0.025
The sizes of the intakes selected in this way for an average value of q = 0.3 provide an improvement in gas separation even for q <0.3, since a decrease in q increases the intensity of reverse currents, expands the thickness of the layer of reverse currents and the amount of gas accumulated in it. At q> 0.3, both the layer thickness and the amount of gas gradually decrease, the intake can partially leave the reverse current zone, and gas separation decreases. To intensify the reverse currents, and consequently, to improve the gas separation at the modes q> 0.3, a conical partition is introduced. In addition to improving gas separation, the conical baffle eliminates completely possible cavitation vibrations in the pump and depending on the diameter of the cone, i.e. by size

, you can improve or worsen the energy performance of the pump. To avoid possible performance degradation, size

chosen so that the cone was not buried in the stream more than the intakes, i.e.

=

+

= (0,02-0,025)+(0,084-0,09) 0,1-0,115
При этом были проведены испытания по выявлению влияния конуса на напорную и кавитационную характеристики насоса и его коэффициент полезного действия. Эффективность газоотделения с конусом существенно возрастает.

=

+

= (0.02-0.025) + (0.084-0.09) 0.1-0.115
At the same time, tests were conducted to identify the effect of the cone on the pressure and cavitation characteristics of the pump and its efficiency. The efficiency of gas separation with a cone increases significantly.

) были проведены испытания при разных величинах

, изменяемых за счет увеличения прокладок S₂. Первоначально, по аналогии с размерами

и

расстояние от заборника D=8,5 мм до конуса было выбрано равным 0,02, при этом получилось

= 0,02 +

0,0625
Однако при увеличении расстояния

до 0,07 количество удаляемого газа увеличилось. При дальнейшем увеличении

Q_ri не менялось. Поэтому в заявке и выбрано

, увеличение расстояния

не повышает эффективности газоотделения, хотя увеличивает осевые габариты устройства.To determine the distance from the intake to the cone (

) tests were carried out at different values

changeable by increasing gaskets S ₂ . Initially, similar to dimensions

and

the distance from the intake D = 8.5 mm to the cone was chosen equal to 0.02, and it turned out

= 0.02 +

0.0625
However, with increasing distance

up to 0.07, the amount of gas removed increased. With further increase

Q _{ri has} not changed. Therefore, in the application and selected

increasing distance

It does not increase the efficiency of gas separation, although it increases the axial dimensions of the device.

The proposed device was successfully used to create a booster pump, pumping aerated liquid with a gas content of δ _in 40% working in a wide range of flow rate parameter q = 0.56-0.16. Table 2 shows the results of evaluating the effectiveness of the proposed device with a prototype. The calculation of the device was carried out for the nominal mode of operation with q = 0.32.

критическое газосодержание на входе в насос, при котором происходит срыв насоса; δ_кр то же с применением устройства, не имеющего конусной перегородки;
Δδ

эффективность заявляемого устройства, показывающая, на сколько можно повысить степень аэрации потока во входном патрубке насоса;
Q_отс.ж. количество жидкости, теряемой при деаэрации потока;
δ _{перег.кр} критическое газосодержание устройства с перегородкой.In the above table, δ _cr.ex =

critical gas content at the inlet to the pump, at which the pump stalls; δ _cr the same with the use of a device that does not have a conical partition;
Δδ

the effectiveness of the claimed device, showing how much you can increase the degree of aeration of the flow in the inlet of the pump;
Q _s.zh. the amount of fluid lost during deaeration of the stream;
δ _overcritical critical gas content of the device with a partition.

 The above data show that a pump equipped with a gas separation device, made according to the recommended sizes, provides a 2-8-fold increase in pump operability on a gas-liquid mixture and, depending on the mode, as well as a significant decrease in working fluid losses during gas suction in comparison with the prototype deaeration flow.

Claims (1)

A LIQUID DEGASING DEVICE, including a vane pump, in which an auger is installed in the inlet pipe, characterized in that, in order to increase the efficiency of the device, it is equipped with conical gas intakes evenly installed around the inlet pipe circumference in front of the auger, which are located in a plane perpendicular to the axis rotation of the pump, with axes parallel to the tangent to the circumference of the pipe at the place of installation of the intakes, the largest diameter of the intake is 0,084 0,09 diameter of the screw, the distance from the edge of the greatest the diameter of the intake to the screw and to the walls of the nozzle is equal to 0.02
0,025 diameter of the screw, while the device is equipped with a prefabricated collector, outlet pipes connecting the intakes and the prefabricated collector, and a partition in the form of a truncated cone installed in the nozzle in front of the intakes, the smaller base of the partition is directed toward the intakes, the axis of symmetry of the partition coincides with the axis of the nozzle, the larger the diameter of the partition is equal to the inner diameter of the nozzle, the plane of the smaller diameter of the partition is located at a distance of 0.1 0.115 the diameter of the screw from the wall of the nozzle, and the distance from the plane is less its diameter to the partition plane axes intakes equal to 0.072 0.100 screw diameter.

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